IBM i5/iSeries Primer(c) Concepts and Techniques for Programmers, Administrators, and Sys[... ]ators

Before you can even consider tackling the interesting and challenging task of developing Java applications, you must understand the basics of the Java language. This section discusses the following:

• Creating Java source files

• Compiling source files into class objects

• Running a Java application

All the examples in this section use the Remote System Explorer (RSE) component of WDSc for iSeries. Drill into the IFS and the Root File System. Create a new folder name i5Primer, then create a new file within that folder named Vehicle.java. Figure 26.3 shows the code for Vehicle.java.

Figure 26.3: Source code for Vehicle Java Class.

Lines of code that begin with // are considered comments.

• The code class Vehicle { identifies the beginning of the source that describes the class named "Vehicle." The first open brace ({) marks the beginning of the code for Vehicle.

• The code public Vehicle() { begins a constructor method for the class. A constructor method is a section of code that creates a new instance of the class. It is possible to have multiple constructors, each one having a different set of arguments (parameters).

• The System.out.println("Vehicle: Ford Explorer"); prints the text "Vehicle: Ford Explorer." Notice that the line of code ends with a semicolon. Most lines of code within the class will end in semicolons.

The first close brace (}) ends the constructor method, and the second close brace ends the class. All classes will resemble this basic format. Examples throughout the rest of this chapter illustrate increasingly complex techniques.